This invention is a rotary machine for treating work surfaces, the fingers impacting the work surface, the effects being to remove the surface finish, clean, polish, or anneal.
Wire brushes and the like provide strands that extend radially due to centrifugal force, and will gouge the work surface if care is not exercised. Because the strand strikes the surface at nearly a right angle, a shearing force is applied to the surface, removing the material at the tip of the strand irrespective of whether such removal is desired or not. Where the strand is made flexible or is composed of articulated links, the end of the strand removes material by frictionally scraping the surface, again with a possible gouging action.
Such machines do not fully take advantage of the physical characteristic differences between the material to be removed and the substratum. They rely either on an inferior shear bond between the two materials, or upon careful and continual visual inspection of extant material.